Strategies for improving milk coagulation properties
Nina Aagaard Poulsen1, Hanne Bak Jensen1, Vivi Gregersen2, Frida Gustavsson3, Maria Glantz3, Carl Emil Aae
Eskildsen4, Henriette Pasgaard Bertelsen2, Mette Marie Løkke1, Thomas Skov4, Guilherme de Moura
Maciel1, Christian Bendixen2, Marie Paulsson3, Bart Buitenhuis2, Lotte Bach Larsen1
1
Department of Food Science, Faculty of Science and Technology, Aarhus University, Blichers Allé 20, P.O. Box 50, DK8830 Tjele, Denmark; 2Department of Molecular Biology and Genetics, Aarhus University, Blichers Allé 20, P.O. Box 50,
DK-8830 Tjele, Denmark; 3Department of Food Technology, Engineering and Nutrition, Lund University, P.O. Box 124,
SE-221 00 Lund, Sweden, 4Department of Food Science, University of Copenhagen, Rolighedsvej 26, DK-1958
Frederiksberg, Denmark
Milk coagulation properties are essential for cheese manufacturing. Within the Danish-Swedish Milk
Genomics Initiative, rennet-induced coagulation properties in milk from individual cows have been
screened in three major Nordic dairy breeds. The screening of coagulation properties showed that there
are large individual differences between cows for these traits. Furthermore, milk from Danish Jersey cows
had the best coagulation properties, whereas approximately 2 % of the Danish Holstein samples could not
coagulate (denoted non-coagulating), and up to 17 % were poorly coagulating. In Sweden, 18 % of the milk
samples from Swedish Red cows were found to be non-coagulating, which is a surprisingly high proportion
that calls for improvement and elimination.
We found a strong association between milk coagulation properties and known variants at the casein
genes on BTA6. In Sweden, common composite genotypes were associated with poor and non-coagulation,
and generally Jersey cows had higher frequencies of variants traditionally associated with improved milk
coagulation. Our recent research has focused on identifying the underlying causal mutation for rennetinduced milk coagulation and these haplotypes are now being validated in a new sample set.
The results provide good opportunities for improving milk coagulation properties through selective
breeding either using a genomic selection approach or gene test strategy. However, this can potentially
affect other important milk quality traits and therefore herds producing milk for specific purposes (e.g.
cheese herds) might be a more attractive approach than including milk coagulation traits in the national
breeding program, which also calls for high throughput phenotyping method using e.g. infrared
technologies.
Moreover, current studies focus on milk coagulation properties mainly from midlactating cows using
various rheological methods, and insights into the interplay between the cow, its genes and the
environment in relation to milk coagulation properties across the lactation period is still scarce.